In one prior art refrigeration unit, as shown in U.S. Pat. No. 5,277,039, granted Jan. 11, 1994, and cited above, a refrigeration unit is disclosed for mounting in a food storage cabinet or structure. The unit has cooling coils, and a centrifugal fan for directing cooled air into the cabinet, and toward food trays mounted in the cabinet. The overall operation of the refrigeration system is of a type generally known, with coolant such as Freon or other similar refrigerant being condensed into a liquid state by an external compressor and condenser, and then supplied to the refrigeration unit. In the refrigeration unit, an expansion valve is provided and the resultant cold refrigerant from the expansion valve is supplied to heat exchange coils. The fan mentioned above draws room temperature air across the coolant coils and directs the refrigerated air toward food pans or other areas where cooling is desired. The expansion valve was located near the fan in the path of cold air from the refrigeration coils.
Under adverse conditions, however, involving high humidity, for example, frost or ice would build up on the expansion valve. With the expansion valve located adjacent to the centrifugal fan and toward the output from the coolant coils, the frost or ice build-up would, on some rare occasions and interfere with the rotation of the centrifugal fan.
The centrifugal fan and the electric motor for it are the only moving parts of the refrigeration unit; and in the system of U.S. Pat. No. 5,277,039 the fan and the electric motor were firmly secured into the entire refrigeration assembly. Accordingly when the fan or electric motor required removal for servicing or replacement, it was a time consuming project.